Monday, August 29, 2005

Stop Using Sunscreen

A very interesting article is in this month's Harvard Magazine (not online yet). The theory is that by using sunscreen, people prevent their bodies from producing Vitamin D, and thereby create a higher risk of several types of cancer, far outweighing the risk of skin cancer. Here are some excerpts:

According to a new theory, sealing our skins off from the sun may cause more cancer deaths than it prevents.

Associate professor of medicine Edward Giovannucci notes that UV-B radiation, the source of suntan and sunburn, is also the component of sunlight that enables human skin . . . to synthesize the "sunshine vitamin" -- D -- used by every type of cell in the human body. Animal research has associated a lack of vitamin D with multiple sclerosis, osteoporosis, and pathological processes that underlie several forms of cancer, including those of the colon, breast, prostate, and digestive tract . . . .

"If you look at the cancers as a group," says Giovannucci . . . "you'll see that 30 people dies of these cancers for every one who dies of skin cancer."

3) Fat people have higher rates of cancer along with lower levels of vitamin D (which is fat-soluble).

4) Black people have much lower levels of vitamin D and higher rates of cancer, particularly prostate cancer. Giovannucci says that in a study of the Health Professionals sample, he was able to control for a wide variety of variables affecting the rates of cancer for white vs. black people, but "the only factor we found that showed a significant difference was vitamin D levels."

Also worth noting: 20 minutes in the sun can produce 10,000 units of vitamin D, which is the equivalent of drinking 100 glasses of fortified milk.

In concluding, Giovannucci says: "More sun, and higher rates of vitamin D, correlate with fewer cancers. It might ultimately prevent only a fraction, perhaps 30 percent, of those cancers it seems to affect. But that would still be vastly more cases than any skin cancers it causes. I don't recommend that people go out and get sunburned -- use common sense. But if the studies hold up, vitamin D will be a relatively important factor, since it affects such a large number of cancers. It may be time to rethink the message we are sending about sunlight."